Fabrics obtained by weaving warps and wefts have conventionally been used widely as an industrial fabric. They are, for example, used in various fields including papermaking wires, conveyor belts and filter cloths and are required to have fabric properties suited for the intended use or using environment. Of such fabrics, a papermaking wire used in a papermaking step for removing water from raw materials by making use of the network of the fabric must satisfy a severe demand. There is therefore a demand for the development of fabrics which do not transfer a wire mark of the fabric and therefore have excellent surface property, have enough rigidity and therefore are usable desirably even under severe environments, or are capable of maintaining conditions necessary for making good paper for a prolonged period of time. In addition, fiber supporting property, improvement in a papermaking yield, good water drainage property, wear resistance, dimensional stability and running stability are demanded. In recent years, owing to the speed-up of a papermaking machine, requirements for papermaking wires become severe further.
Since most of the demands for industrial fabrics and solutions thereof can be understood if papermaking fabrics on which the most severe demand is imposed among industrial fabrics will be described, the present invention will hereinafter be described by using the papermaking fabric as a representative example.
For papermaking fabrics, excellent surface property not permitting transfer of wire marks of the fabric to paper, fiber supporting property for supporting fine fibers, running stability ensuring stable running until the final using stage and rigidity are very important. Research on the design or constitution of the fabric capable of satisfying the above-described properties is proceeding. Recently, two-layer fabrics using a warp binding yarn which is woven with both an upper surface side weft and a lower surface side weft to form an upper surface side surface and a lower surface side surface and at the same time, has a binding function have come to be used. A two-layer fabric using a warp binding yarn is also disclosed in Japanese Patent Laid-Open Publication No. 2004-68168. This fabric does not use an additional binding yarn. Since it has a design in which a warp forming a surface passes over one upper surface side weft and then passes under three upper surface side wefts, the count of wefts can be increased, leading to the formation of a dense surface. As a result, the fabric has improved surface property and fiber supporting property. As described above, however, this fabric has a design in which a warp forming a surface passes over one upper surface side weft and then passes under three upper surface side wefts so that the number of knuckles which are intersections of warps and wefts is small and therefore the fabric has poor rigidity. Its running stability sometimes gradually deteriorates. A fabric developed with a view to improving its rigidity is disclosed in Japanese Patent Laid-Open Publication No. 2004-52188. By employing a plain weave design for the upper surface side according to this invention, the resulting fabric is able to have improved surface property, fiber supporting property and rigidity.